Metallurgical alloy



Patented Dec. 23, 1941 UNITED STATES PATENT OFFICE METALLURGICAL ALLOY Viatcheslav V. Efimofl', Niagara Falls, N. Y., as-

signor to The Titanium Alloy Manufacturing Company, New York, N. Y., a corporation of Maine No Drawing. Application October. 10, 1940, Serial No. 360,623

3 Claims.

This invention relates to new and improved alloys suitable for addition to steels containing chromium, particularly stainless steel (18% chromium, 8% nickel) and chromium steel.

in the ore from which the alloy is produced. However, it is important to insure that too much silicon is not present, since it tends to form a coarse-grained steel and to impair, the impact amount of excess titanium to insure complete combination with all the carbon. These results have hitherto been accomplished by adding to the steel at the ladle a small amount of a ferro-titanium alloy (called a metallurgical alloy) containing enough titanium so as to secure the required amount in the finished steel. Such alloys obviously contain as small an amount of carbon as is conveniently practicable, since such steels should have a very low carbon content. Furthermore, the titanium content should be as high as conveniently possible, in order to avoid adding too large an amount of cold metal to the molten steel just'before pouring, giving too low a. pouring temperature. In practice, an alloy containing about 40% titanium has been found to produce excellent results on an economical scale;

One of the difficulties occasionally encountered in the use of such ierro-titanium is the tendency for titanium to combine with nitrogen in the air and with carbon to form titanium cyanonitride, an undesirable compound to be incorporated in chromium steels, since it promotes hard spots, seams, and a rough appearance to the ingot, or alligator skin.

The present new and improved alloy overcomes this and other dificulties, and at the same time serves as a source of art of the chromium in the finished steel. In accordance with this invention, chromium is incorporated with the iron and titanium to form a metallurgical alloy containing iron, titanium, and chromium. By this means, nitrogen in the alloy apparently combines with chromium to form chromium nitride, ,a compound which is stable at high temperatures. The nitrogen is thus largely or completely made col unavailable for combination with titanium, so

that no titanium cyanonitride can exist to form hard spots, seams, or other defects.

In addition to titanium, iron and chromium, the present alloy contains appreciable amounts of silicon, aluminum and carbon. The carbon is present as an impurity, and is kept as low as possible. The aluminum is present because the alloy is prepared by the alumino-thermic process, or because it is present in the ore from which the alloy is produced. Silicon is also usually present.

resistance of the steel, and in the case of stainless steel to promote the formation of ferrite.

The percentages of the various ingredients in the present new and improved alloy are as follows:

Per cent Titanium l 35 to 45 Chromium Q 2 to 14 Silicon 1 to 14 Aluminum 3 to 14 Carbon Below 0.2 Iron plus impurities (phosphorus, sulfur, etc.) Balance More preferably, the ranges of these ingredients areas follows:

The alloy according to the present invention can be made by any convenient method. Preferably it is made by reducing the titanium ore such as ilmenite and rutile, together with a suitable quantity of a chromium containing ore such as chromite, with aluminum by the alumino-thermic process.

Some sources of raw ilmenite contain appreciable quantities of chromium ore as an impurity, and most sources contain a certain amount of silicon. Accordingly, ilmenite often serves as the source of silicon and some of the chromium.

The invention having been described generally, the following specific example is now given:

Example contained 48.92% Cl'zOa, 14.0% F6203, 16.46%

cording .to U. S. Patent No. 2,162,938 and con- Per cent Titanium 41.1 Chromium 10.17

Aluminum 7.0 Silicon 2.99 Carbon p 0.03 Iron plus impurities Balance The alloy of the present invention is added to the steel in any convenient way, particularly adding the alloy to molten steel in the ladle.

As many variations are possible within the scope of this invention, it is not intended to be limited except as defined by the appended claims.

What is claimed is:

1. A metallurgical alloy containing 35 to 45% titanium, 2 to 14% chromium, 1 to 14% silicon, 3 to 14% aluminum, less than 0.2% carbon, and the balance iron plus impurities.

2. A metallurgical alloy containing 38 to 42% titanium, 3 to 14% chromium, 2 to 5% silicon, 6 to 9% aluminum, less than 0.1% carbon, and the balance iron plus impurities.

3. A metallurgical alloy containing about 41% titanium, about 10% chromium, about 7% aluminum, about 3% silicon,-about 0.03% carbon, and the balance iron plus impurities.

VIATCHESLAV V. EFIMOFF. 

